TYyvevegy 
The formula AP = =(k,P + k, | P) (3) 
used in cadastral practice for differences between the 
results of two areal measurements of a parcel has 
been derived empirically from the differences attend- 
ing multiple area measuremen's of variously sized 
parcels. Hence it is no criterium of differences be- 
tween the true area of a parcel and its acreage deriv- 
ed from the map. Potuzák [5] emphasized this short- 
coming and the fact that the areas are not derived 
from the valid criteria of the measured lengths 
As = =(0.00015s + 0.005 Vs + 0.015) . (4) 
In dependence on the mean planimetric errors 
mxy of the boundary points, 
my — - 0.10 m for maps on a scale of 1:1000, 
My = = 0.17 m for maps on a scale of 1:2000, 
and 
My = = 0.28 m for maps on a scale of 1:5000. 
Adámek [1] writes at present formulas for the 
mean errors of parcel areas analytically calculated 
irom geodetical coordinates: 
mp = = 0.10 VP [m?] for a map on a scale of 
1:1000, 
mp = = 0.17 VP [m?] for a map on a scale of 
1:2000, Uc 
mp = + 0.28 VP [m°] for a map on a scale of 
1:5000. (5) 
According to Adámek [1], two parcel measurements 
based on maps may differ by the following maximum 
permissible errors: 
AP — «0.21 VP + 3 [m?] for a map scale of 
1:1000, 
AP = = 0.42 VP + 6 [m?] for a map scale of 
1:2000, 
AP = + 1.05 VP+14 [m°] for a map scale of 
1:5000. (6) 
The statistical data listed in Table 2 were used 
to determine the relations between the areal accuracy 
of photogrammetrically plotted parcels on the one 
hand, and the image scale and the true size of the 
parcel on the other. If we assume that the quadran- 
gular parcels under investigation are squares of side 
length d determined with a mean error of m,, then 
(according to the law of the accumu'ation of errors) 
the area P is determined with a mean error mp 
m= =2m, VP. (7) 
  
  
  
  
  
  
Table 3 
Mean areal errors of parcels plotted photogrammetr:cally by the 
Map scale ro hical 
1:Mk numerical graphica 2 
method 
1:1000 mp = «0.08 VP Xmp = «0.15 Y P 
1:2000 mp = «0.14 VP (8) mp = «0.25 yP (9) 
1:5000 XXmp — «0.25 | P mp = «0.41 | P 
Notes: 
X This dependence is determined by analogy with the map scales 1:2000 and 1:5000. 
XXX All the image scales investigated (1:13,370, 1:15,000, 1:20,000 and 1:25,000) 
were taken into consideration in the computation o the mean errors of parcel areas. 
  
  
  
Table 3 shows the mean areal errors of the par- 
ce's mp as functions of the parcel areas P, calculated 
from the data of Table 2 by the meihod of leas! 
squares — maps on the scales of 1:1000 (1:2000 
and 1:5000) having been plotted from image scales 
of 1:3500 to 1:5000 (1:7000 to 1:9000, and 1:14,000 
to 1:25,000, respectively). 
The agreement of Eqs. (8) (derived from photo- 
grammetric plottings) with Eqs. (5) (based on theo- 
retical considerations) bears out that the accuracy of 
plenimeiric plotting is higher than that of geodetic- 
ally surveyed poin's as estimated by Adámek. 
The me?n error my of photogrammetrically de- 
termined distances d can easily be found from Egs. 
(8) for the mean areal errors of photogrammetrically 
plotted parcels. If, according to (7), 
Mp. == 2 my VF, 
then the mean error my of the photogrammetrically 
determined distances [expressed on the image scale 
of mg = 1:M,] is 
Mp 
“2PM. [ um | : ( 10) 
mg — 
The values of my for the map scales and image scales 
considered in our investigation are listed in Table 4. 
After graphical plotting, the values of mean errors 
mq are about 70 96 higher. 
The values of the mean errors of photogram- 
metrically determined distances, derived from the 
mean areal errors of numerically plotted parcels, bear 
out the relatively high accuracy of aerial photogram- 
metry and are in very good agreement with the re- 
sults of earlier work and Refs. [2] and [3].